Cancer is the second leading cause of death in the United States. The National Cancer Institute estimates that about eight million Americans have a history of cancer. In the United States, about 1 million new cancer cases are diagnosed each year, and about 500,000 individuals die of cancer each year.
However, between 1992 and 1998, the cancer death rate in the United States fell by 1.1%. This reduction is at least partially attributed to an early detection and diagnosis of a cancer, and an earlier treatment regimen, which can lead to a greater likelihood of cure. Medical imaging has become vital in the early detection and diagnosis of cancer, which may allow a cancer treatment to begin before the cancer metastasizes to other body tissues and organs. In many cases, if a cancer is detected sufficiently early, an early treatment can lead to a complete cure.
Cancer research and diagnosis both are critically dependent on imaging technologies. Imaging advances already permit remarkable accuracy in (a) detecting whether a tumor has invaded vital tissue, grown around blood vessels, or spread to distant organs; (b) allowing physicians to monitor patient progress without the need for biopsies; and (c) allowing a precise delivery of tumor-destroying agents to the tumor site. Computed tomography (CT) imaging, magnetic resonance (MR) imaging, mammography, nuclear medicine (NM) imaging, ultrasound (US) imaging, and X-ray imaging are important imaging tools in achieving these goals.
Pharmaceutical compounds administered by intravenous, oral, or rectal routes often are termed “contrast agents,” and sometimes referred to as a “dye.” A contrast agent is used to make specific organs, blood vessels, and/or tissues “stand out” with more image contrast in order to more definitively reveal the presence of a disease or injury. Thus, a contrast agent high-lights specific areas of the resultant image, or “dyes” the image. The use of contrast agents greatly improves the ability of imaging techniques in the detection and diagnosis of cancer, and improves the prognosis of a recovery by the patient. For example, gadolinium-DTPA enhanced MRI and CT, with or without a contrast agent, are commonly used in the detection of solid tumors.
The present invention is directed to the use of an endothelin ETB receptor agonist or an endothelin ETA receptor antagonist, in combination with an imaging agent, to enhance a diagnostic method of detecting a tumor.